Incidence and etiology of lumbar spondylolysis: review of the literature.

BACKGROUND: Lumbar spondylolysis is a defect of the pars interarticularis known to occur as a stress fracture. Its incidence varies considerably depending on ethnicity, sex, and sports activity. However, there are few literature reviews describing its incidence in different ethnic groups or in people who engage in different sports. METHODS: We reviewed the most relevant articles on spondylolysis published in scientific journals. First, we focused on its incidence in various ethnic groups distributed by sex, the familial occurrence, and in patients with relevant diseases. Second, we focused on the incidence of spondylolysis in relation to the sports practiced by the patients. Although placing special emphasis on the incidence of lumbar spondylolysis in the general population in Japan, we also reviewed the Japanese and English literature to investigate its incidence among those who engage in different sports. RESULTS: The incidence of lumbar spondylolysis in the general Japanese population was 5.9%. Most studies report that the incidence in higher in male subjects than in female subjects. We found that Japanese rugby and judo players were prone to suffer lumbar spondylolysis, at an incidence of about 20%. However, the incidence for Japanese professional soccer and baseball players was much higher, at 30%, which was more than five times the incidence in the general Japanese population. CONCLUSIONS: The incidence of lumbar spondylolysis varies depending on ethnicity, sex, family history, relevant disease, and sports activity.

Sacral orientation and spondylolysis.

STUDY DESIGN: A descriptive study (based on skeletal material) was designed to measure sacral anatomic orientation (SAO) in individuals with and without spondylolysis. OBJECTIVE: To test whether a relationship between SAO and spondylolysis exists. SUMMARY OF BACKGROUND DATA: Spondylolysis is a stress fracture in the pars interarticularis (mainly of L5). The natural history of the phenomenon has been debated for years with opinions divided, i.e., is it a developmental condition or a stress fracture phenomenon. There is some evidence to suggest that sacral orientation can be a "key player" in revealing the etiology of spondylolysis. METHODS: The pelvis was anatomically reconstructed and SAO was measured as the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis (PUBIS).SAO was measured in 99 adult males with spondylolysis and 125 adult males without spondylolysis. The difference between the groups was tested using an unpaired t test. RESULTS: Spondylolysis prevalence is significantly higher in African-Americans compared to European-Americans: 5.4% versus 2.04% in males (P < 0.001) and 2.31% versus 0.4%, P < 0.001 in females. SAO was significantly lower in the spondylolytic group (44.07 degrees +/- 11.46 degrees) compared to the control group (51.07 degrees +/- 8.46 degrees, P < 0.001). CONCLUSION: A more horizontally oriented sacrum leads to direct impingement on L5 pars interarticularis by both L4 inferior articular facet superiorly and S1 superior articular facet inferiorly. Repetitive stress due to standing (daily activities) or sitting increases the "pincer effect" on this area, and eventually may lead to incomplete synostosis of the neural arch.

Spondylolysis and associated spondylolisthesis in Eskimo and Athabascan populations.

Roentgenographic and anthropologic studies have shown a high incidence of spondylolysis in Eskimo populations. It is uncertain whether this is related to a genetic predisposition or to environmental factors. This study of recent roentgenograms and demographic characteristics of patients of the authors' institution notes a lower incidence in Eskimo populations than prior skeletal and roentgenographic studies. An attempt is made to quantitate the contributions of environmental factors and genetic predisposition. A higher incidence was found in full-blooded Eskimos than in part-blooded Eskimos. Rural-dwelling Eskimos had a higher incidence than urban-dwelling Eskimos. Eskimo subpopulations had a greater incidence than Athabascan Indians. Eskimos with spondylolysis were significantly more likely to have an associated spondylolisthesis than Athabascans with spondylolysis. Symptoms in the Eskimo population related to spondylolysis and associated spondylolisthesis rarely warrant surgical intervention.